Date of this Version
PHYSICAL REVIEW D 84, 052007 (2011); DOI: 10.1103/PhysRevD.84.052007
We present an updated measurement of the anomalous like-sign dimuon charge asymmetry AbSl for semileptonic b-hadron decays in 9.0 fb-1 of pp collisions recorded with the D0 detector at a center-of-mass energy of √s= 1.96 TeV at the Fermilab Tevatron collider. We obtain Absl = (-0.787 ± 0.172 (stat) ± 0.093 (syst)) %. This result differs by 3.9 standard deviations from the prediction of the standard model and provides evidence for anomalously large CP violation in semileptonic neutral B decay. The dependence of the asymmetry on the muon impact parameter is consistent with the hypothesis that it originates from semileptonic b-hadron decays.